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Checking for a new Dell server for SMB. Will be used for ESXi.

ESXi will be loaded on IDSDM SD cards, since it has very little foot print.

Will be using RAID 10 with local drives.

All our old servers had SAS 10K or 15K drives.

Now with new server Dell gives options for both SATA SSD and SAS SSD’s. The later seems expensive for us.

Now the question is how much of a performance boost do you see between the following two types:

SAS 15K drives Vs. SATA SSD

I know it might depend on our workloads, but wanted to hear from spiceheads in this group who already did that and if they had seen any performance gains after migrating from SAS 15K drives to SATA/SAS SSD’s

Any other suggestions are welcome, Thanks for your time.

11 Spice ups
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It really does depend on the work load… but I’d still look at the SSDs. Price wise you won’t save much going 15K drives. Especially if you factor Raid5/6 SSD vs Raid 10 for the 15K drives. I don’t have raw numbers and it’s been sometime since we moved production VMs to SSD drives. But for sure with SSDs the storage most likely will not be the bottleneck. It will be the Raid controller or the network. (or CPU or Ram, again - depending on the workload)

3 Spice ups
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15K SAS drive’s sustained throughput can be up to about 300 MB/sec before hitting mechanical limits (can only spin so fast).

A SATA SSD can sustain 500-600 MB/sec, maxing out the SATA III speed of 6 Gbps.

Go a step further and you can consider SAS SSD drives. I have my SAN filled with those. If connected to 12 Gbps interfaces you can easily get SAS SSD drives that will sustain reads and writes of the full interface speed of 12 Gbps aka some 2,200 MB/sec.

Going from spinning SAS to SSD SAS has made an incredible difference. If budget allows for it, I would highly recommend. Of course consider the rest of your infrastructure to make sure you can take advantage of the speeds. Your bottlenecks may be elsewhere.

6 Spice ups
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For 2-3 years a Dell server with 3 or more RI SSD in RAID 5 will cost less than the same server using 10K SAS in RAID 10 for the same usable capacity. There is basically no use case anymore where 10K or 15K SAS is better than SSD. When SSTA SSD is cheaper, faster, and more reliable, SAS HDD make no sense.

3 Spice ups
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For old SAS 15K drives we used RAID 10 .

If we go with SATA SSD what type RAID you reccomend ?

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Also keep in mind the TYPE of SSD you get. Some are designed for read-intensive use, some for write-intensive use, and some for balanced use.

Gregg

2 Spice ups
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The other thing to keep in mind is IOPS performance. Even with 6Gbps SATA SSD’s, vs 12Gbps SAS HDD’s, your IOPS performance is going to be orders of magnitude higher with the SSD’s. With the cost of SSD’s having come way down over the last couple of years, there really is no reason to even consider 15K HDD’s anymore.

1 Spice up
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Another question to answer is do you need SAS. In my use case for example the JBOD that houses my drives needs to have multipath capable disks because two SAN nodes in a High Availability cluster will both address drive. That’s not something SATA can do.

If that’s not in use, you might be able to get away with SATA vs SAS as Kevin stated.

2 Spice ups
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For bandwidth you go for tape, flash is killing spinning disks when it comes to seek time (non existing for flash) and I/O latency.

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Yesterday, I read the announcement of 30 TB SAS SSD drvies for almost full SAS interface speed of 24 Gbps from Kioxia. This announcement didn’t include prices nor availability though.

2 Spice ups
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SAS is history. NVMe :slight_smile:

4 Spice ups
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Are you offering free JBOD upgrades/replacements to NVMe capable ones? :smiley:

2 Spice ups
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First thing to consider is how often you turn over your systems and if you care about Warranty. Dell does not cover SATA disk for more than 3 years regardless of your Warranty length! (If you buy a new server with 10 SATA SSDs and extend the warranty to 5 years, the disk warranty expires at 3 years. If you bought it with SAS SSD or SAS 15k the disks would be covered under the warranty.)

That aside, all things being equal, I would ALWAYS buy SSDs. Even 1DWPD SATA SSDs are likely going to outperform 15k SAS spinning rust in latency and match them in throughput when you setup a RAID on a good controller. Plus, you don’t have to worry as much about a puncture with SSDs so it’s going to save you physical disks.

The other thing about 15k SAS is that they’re EXCEPTIONALLY hot. In my experience, even high quality 15k SAS fail simply because they’re crammed into a chassis in a room that does not have ADDITIONAL cooling. This brings you to power for cooling, power for the disks themselves, etc etc etc.

SSDs aren’t new tech anymore. There’s really no reason to use spinning rust for anything anymore unless you either 1) Simply cannot afford it. 2) Need the extreme capacity that spinning rust provides (aka, you can’t afford it).

3 Spice ups
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You old JBODs won’t have enough of the lanes to support newer SAS devices @ full speed either way.

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That is good to know.

How come Dell covers only for max of 3 years warranty on SATA SSD’s ? are they prone to more failures compared to SAS SSD and SAS 15K drives ?

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Well I don’t know the exact models of disks that they use for SSDs but the SATA spinning rust they use is generally pretty much junk. All OEMs use pretty much the cheapest equipment that will get them reliably through to the end of the warranty. If you buy a computer with a 1 year warranty, it’s not going to have a WD Black hard drive, it’s going to have a white labeled green or some kind of Hitachi or Seagate rebrand green disk.

Pretty much the only SATA spinning rust that I have ever had last reliably in a RAID for even 5 years is WD GOLD drives and they’re nosebleed expensive as hard drives go. I doubt you’re getting a ‘5DWPD’ equivalent SATA SSD with a white label on it, even if you spend extra for it. RAID is going to put a lot of writes on an SSD.

Just compare the pricing of a 1DWPD SAS SSD vs a 1DWPD SATA SSD. The interface card is of nominal cost. The rest of that cost is obviously to make the memory and wear leveling much better. Same for SAS spinning rust. Just more free sectors for reallocation available (which means a more reliable disk).

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How do you come to that conclusion, for which SAS configuration and version?
These SAS-4 drives will become available by end of August 2020. I wouldn’t call that history. According to the press announcement, when connecting these drives with two cables to PCIe 4.0 with 4 lanes, the full speed of 4.3 GBytes/s may be reached. As far as I know, most NVMe SSDs remain below while very few may reach about the same speed.
And do you consider SAS-5 also history? Which speeds and IOPS may be expected with SAS-5? Or did you only refer to SAS-1, ignoring the fact that I obviously referred to SAS-4 while most SAS controllers today are either SAS-2 or SAS-3?

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My guess is Dell is just using the OEM warranties.

The actual failure rates will depend on environment as much as manufacturing, and SAS drives are generally used in better controlled environments, so have lower replacement rates than SATA, which are used in pretty much anything.

Warranties are always about cost versus benefit, and someone somewhere did a spreadsheet to figure out the best warranty length to minimize losses.

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(a) SAS has SCSI conversion layer NVMe doesn’t have (overhead! OS doesn’t need to translate reads and writes to SCSIOP and device doesn’t need to do it back, it’s system NVMe driver @block (Linux) or @class (Windows) level talking to the actual hardware in the language it understands - NVMe protocol) and (b) doesn’t have multiple long (2^16) I/O queues (c) bound to CPU cores ← These b+c iare HUGE. SAS device has no relationship to OS (it’s kind of a black box to it…) and NVMe device does, you can balance CPU and IOPS the way you need, which is critical. You ignore operational latency with your rampage sales pitch and latency this is where all the magic happens, if you focus on bandwidth you just pack tons of LTO8 tapes and drop them from the roof - nobody is going to beat you up.

3 Spice ups
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I made an excel sheet with some price comparison for the Hard drives while spec’ng out the Dell server. To see which one fits our needs.

Dell_SSD_drives_comparsion.jpg

DWPD_and_TBW__SSDs.jpg